Fluid injector



Aug- 17, 1965 R. c. sAUNDE-Rs, JR 3,200,764

FLUID INJECTOR Filed Sept. l0, 1962 2 Sheets-Sheet 1 Raaf/w C. SAUNDERQJR.

nT-romvfa/s lAllg. 17, 1965 R. c. SAUNDERS, JR 3,200,764

FLUID INJECTOR 2 Sheets-Sheet 2 Filed Sept. l0, 1962 my Mm 5 n 5 E w wf uw@ n. a 5 l., a TM5, e E e o RW J.

United States Patent O assegna FLlUlD HNECTR Robert C. Saunders, lr., 2d Fair Galas, St. Louis 24, Mo. lli'iierl Sept. lil, 1962, Ser. No. 222,719 23 (Ilaims. (Cl. MiG-264) This application is a continuationdnpart of my application Serial No. 206,829, liled Iuly 2, 1962, now abancloned.

The present invention relates to a fluid injector or iluid pump. This specic injector is designed to produce a high discharge pressure, generally but not necessarily in excess of the drive iluid pressure. lt has in common with other injectors the use of a high velocity drive fluid to impel a suction liquid. Distinctive features of the pump are that all the drive iluid vapor is condensed or dissolved before discharge from the pump; there is an extended free space gap wherein a certain critical phase of the condensation process takes place, and there is a supersonic diffuser of original design into which the mixed fluid ilows. A typical drive iiuid for this device might be saturated water at high pressure. There are many liuid systems to which this sort of injector may be applied, but for convenience, the description herein will employ a water-steam injector as an adequate, but not limiting, example.

The present injector has a driving liuid nozzle, a mix* er or combining tube, and a delivery tube through which there is sequential fluid llow. The axially enlarged free space, considerably greater than the conventional overilow gap, is downstream of the outlet of the mixer tube. Downstream of the free space is a supersonic dilfuser. The supersonic ditfuser has a convergingdiverging cross-sectional area and a center spike to effect the proper shock pattern in the entering supersonic iluid for ellicient diffusion.

In this invention, the driving fluid nozzle and surrounding driven tluid inlet are arranged so that the driving iluid emits at high velocity into the driven liquid and produces a vapor-liquid stream through the mixing tube. Therein the velocity of the driven fluid is raised while the driving fluid simultaneously loses velocity and is condensed. In the present design the stream leaves the mixing tube at a predetermined, nearly uniform minimum velocity, and jets out across a free space at substantially the pressure at which the driven fluid was initially entrained.

The velocity attained within the mixing tube is important, as is the degree of condensation of the driving fluid. The sonic velocity of a lluid-vapor mixture varies with the quality of the mixture. At 1.0 quality of steam, for example, it is moderately high, being about 1300 fps.; as the quality declines, sonic velocity declines until it reaches a minimum of about 7) fps. at a quality of about 10-3; and then it rises rapidly to a high value of about 5G00 fps. at a quality of 0.0.

In the present invention, the mixture within the mixing tube is brought to a velocity that is actually below sonic velocity at the quality within the tube, but which velocity can become .supersonic upon further reduction of quality at that pressure.

In this `arrangement the momentum transfer is substantially completed by the downstream or outlet end of the mixing tube, but the condensation absorption or adsorption of the driving fluid is incomplete. Hence conditions within the mixing tube are subsonic and uncomplicated by supersonic effects. Yet as the stream jets across the free space, the condensation continues, and hence the quality declines. After a predetermined distance, the quality change so reduces the sonic velocity of the mixture that the velocity of the stream, that formerly was below sonic velocity, rises above sonic velocity,

although there is usually little absolute velocity change in this stage.

Therefore, at a point in the free space, conditions change from subsonic to supersonic. After that change, the system then takes advantage of the fact that pressure increases can be derived by controlling flow conditions. The stream is caused to impinge upon a spike, which causes a conical shock or pressure wave in the stream. Further shocks or pressure waves are initiated by bends in the spike, the diffuser exterior walls and reflections of existing shocks. The spike serves the function of preventing a detached normal shock which would seriously disturb the flow characteristics of the system. The dif fuser has walls converging downstream towards a throat. The series of pressure waves produced in the supersonic fluid increase its pressure and decelerate it as it lows to the throat. Thereafter the liquid expands again under subsonic conditions to produce high discharge pressure at reduced velocity.

There are starting problems in the supersonic injector that are overcome herein. Because of the two-phase nature of the ow and the entrainmcnt of a suction liquid, a diffuser throat larger than optimum is required for starting. In the present arrangement, automatic adjustment of the throat area is provided, so that the area accommodates itself to the starting and running conditions.

Objects oi the invention are: to take advantage of supersonic velocities to obtain higher ultimate injector discharge pressures than heretofore; to control the production of supersonic activities so that they do not occur prematurely, and particularly to prevent their occurrence in the mixing tube; to obtain the last-named objective by developing a velocity in the mixing tube that is subsonic for conditions in the tube but that .may become supersonic under conditions downstream of the mixing tube, and especially to do so by regulating the condensation and momentum transfer in the mixing tube so that further condensation downstream of the mixing tube may change the quality of the mixture at its velocity from subsonic to supersonic conditions. Thereafter it is an object to employ the supersonic velocity to produce pressures in the diffuser higher than those attainable under the normal injector subsonic conditions, and finally to convert to subsonic conditions.

It is also an object to provide for adjustment preferably automatic, of the throat area of the diffuser to improve starting characteristics.

Other objects will appear from the description to follow.

In the drawings:

FIGURE 1 is a sectional View of a typical injector 0r jet pump showing the present invention;

FIGURE 2 as a graph of a typical curve of sonic velocities in steam of varying quality, the values being graphed logarithmically to save space;

FIGURE 3 is a diagrammatic view of a modified diffuser;

FIGURE 4 is a sectional view similar to FIGURE 1, of a modied form of diifuser section, with adjustable throat;

FIGURE 5 is an upstream end View of a diffuser element used in the embodiment of FIGURE 4; and

FIGURE 6 is a downstream end view of the diifuser element of FIGURE 5 As illustrated, the injector comprises a head or nozzle base lil through which an axial passage i1 extends. This passage Til may be threaded in part, to receive a correspondingly threaded nozzle l2. The nozzle l2 may be turned on its threads inwardly or outwardly of the head lil to adjust it. A backing plate 13, with appropriate sealing or packing means such as the O-ring illustrated, is bolted to the head in a manner to prevent leakage of fiuid from the passage 11. The nozzle 12 has a tubular part 14 of reduced diameter projecting beyond the passage 11. The interior of the nozzle is preferably formed with a somewhat conical surface 15 diverging from a throat to its discharge end. This divergence accommodates the fiow of the driving fiuid at supersonic speeds, with velocity increasing toward the outlet.

The head 10 also has a liquid or driven fluid inlet 16 that connects into the passage f1 so that liquid may be introduced around the outside of the end 1d of the nozzle.

A mixing section 19 is attached, as by bolts, to the outlet side of the nozzle head 1f). it provides a mixer tube 29 having an inside diameter somewhat larger than the diameter of the driving fiuid nozzle outlet 1li. The mixer section has a anged entrance end 21 and a fianged outlet end 22. (The ends may sometimes be referred to as upstream and downstream, both on this and other parts, as well as on the overall device.) The downstream end of the mixing tube 29 opens into a free space to be described, the downstream end of which is formed by the flanged end 25 of a combined supersonic diffuser and delivery section base 26. The details of the latter will be described hereafter.

The flange 25 of the diffuser section 26 faces the fiange 22 of the mixing section 19. A plurality, such as three, tubular spacers 32 are disposed between the facing fianges 22 and 25 to fix the distance between them. The spacers comprise sleeves fitted over rods 33. Each rod 33 is fixed at one end in the fiange 25, extends through its spacer 32, through the fiange 22 and beyond the last is threaded to receive a nut 34. By this means, spacers of other lengths may be substituted for those illustrated, to alter the gap or free space between the mixer and the delivery sections. It should be noted that the drawing should not be scaled for the axial length of this gap. Actually it should be about half again as long as shown.

The fiange 2l on the mixer section 19 and the flange 25 on the diffuser section 26 constitute supports for an outer shell 35, that is fitted over them and sealed as by O-rings illustrated, toginsure a fluid tight chamber 36 between the fianges and including the free space between the mixing tube and the diffuser. The shell can slide on the flange 25 to accommodate alterations in the spacers 32.

The free space chamber 36 operates at the pressure existing at the outlet of the mixing section 19, normally about atmospheric, and there is a means to educt condensed stagnant liquid from this space. This comprises a plurality of passages 4@ around the inlet end of the passage 20, that extend outwardly and axially into valve chambers 41 in the fiange 21. Buoyant ball check valves 42 are located in the chambers 41, being confined therein by externally threaded perforated nuts 43. These check valves seal the passages lfb except when the buoyant force of condensed liquid in the chambers 41 causes them to lift. For proper operation of this particular method of removing condensed stagnant liquid, the pump must be aligned such that gravity forces the ball check valves against the passages 40. However, the ball valves 42 are not essential to operation of the apparatus, it being practical to operate it with the passages it? continuously open.

The diffuser section 26 is generally circular in section and coaxial with the nozzle and mixer that also preferably are circular. The diffuser section 26 opposite its flanges 25 has an enlarged outlet portion 44. A cylindrical passage 46 coaxial with the mixer tube 20 extends through the diffuser section 26, and opens into an enlarged chamber 47 in the enlarged head 44 on the section 26. An outlet or discharge passage 48 leads laterally from the head 44 and is to be connected to the receptable for the liquid under the generated pressure of the injector. The chamber 47 is closed by a head 49 bolted and sealed over the end of the diffuser section 26.

T he passage 46 through the diffuser section 26 receives a diffuser element 59. The diffuser element can take the form of a cylinder fitted slidably within the passage 46. A fiange 5l may be provided on it, engageable against a shoulder in the delivery section 26, with an O-ring if it is found necessary to seal the outside of the diffuser 59 and the inside of the passage 46. The closure plate engages the extreme end of the diffuser tube 59 and forces the fiange of the diffuser against the shoulder on the delivery section 26 as shown.

The diffuser 56 has at its upstream end a conical inlet that can provide an entry edge 52, and a conical surface 53 that converges in a downstream direction, to a throat 54. From the throat, the surface is a diverging cone 55 extending to a discharge pressure chamber 56 having lateral outlet openings 57 through which the fiuid may discharge into the surrounding outlet chamber 47 from which the high pressure exit 43 leads.

The diffuser 5ft is provided with a diffuser spike 62 that can be adjustably threaded and secured into the end closure plate 39. From the plate it projects axially upstream through the diffuser, across the discharge chamber 47, to the conical sections 53, 54 and 55. Thereat it is reduced in diameter across the throat 54 as shown at 64, then enlarged at 65, and finally sharpened upstream into a point 66. The point 66 is located out into the free space between the mixing tube 2th and diffuser section flange 25. It may be provided with adequate lateral supports.

Other types of diffusers may be used. For example as shown in FIGURE 3, the diffuser has a tube '70 that may be of constant diameter, with an axially disposed spike 71 expanding at an increased half-angle of divergence, such as 20, from a point '72 to a waist 73. Thereafter it converges at 74. Study shows that this gives passages equivalently shaped to those in FIGURE 1. Other similar designs can be used.

In the modified diffuser section shown in FIGURE 4, as in FIGURE l, the shell 35 slidably receives the flanged end of a diffuser section 99 of circular section. Opposite the fiange 85 the diffuser section 99 has an enlarged outlet portion 91. A cylindrical passage 92, coaxial with the other main parts of the structure, extends through the diffuser section and opens into an enlarged circular recess 93 that is in the head 91. An outlet or discharge passage 94, corresponding to the discharge passage 48 in the first embodiment, leads from the recess or chamber 93. The recess 93 is closed by a head 95 that can be bolted and sealed over the end of the diffuser section 90.

The cylindrical passage 92 through the diffuser section 9@ receives a diffuser element 98. This element is preferably circular in cross section and is slidable within the passage 92. The diffuser element has a head in the form of an outstanding fiangelike portion 99 that is slidable axially withinl the recess or chamber 93. The head 99 is narrower in its axial dimension than is the chamber 93 to permit a limited amount of sliding movement of the diffuser element 98 within the passage 92 and the recess 93. If desired, a seal, such as an O-ring, may be provided between the head 99 and the walls of the chamber 93.

Three equally spaced holes 102 are formed in the head 99 and open to the left in FIGURE 4. Each of these receives a coil spring 103 that seats in recesses 194 in the diffuser member 90. By means of the coil springs, the diffuser element 98 is yieldably urged to the right in the drawing until it engages an abutment on a head 95.

In order to keep the diffuser element 9S from rotating within the section 90, appropriate means such as a pin and a hole may be employed. FIGURE 6 shows a hole 197 that can be used for this purpose, the same to cooperate with an appropriate pin secured to the head 95.

As in FIGURE 1, the spike 105, threadedly adjustable in the head 95, has a red-uced neck portion 166 to the left of which is a tapered section 197 of conical shape. To the left of the section 197 is an oppositely tapered conical section 108 terminating in the sharp point facing upstream.

The diffuser element 98 has a shaped passage through it. At the upstream end this passage includes a conical converging section 110 at the small end of which is a restricted throat 111. This throat 111 is disposed, generally speaking, adjacent the narrow neck 106 of the spike 105. Downstream from the throat 111, the diifuser di verges in a conical wall 112 that feeds into a section 113 that may be cylindrical. This section 113 opens into a transverse passage portion 114 that opens into the outlet 94.

It will be seen that the spike 105 can be threadedly adjusted in the head 95 to dispose its neck 1li-'6 properly with respect to the throat 111 of the diffuser element. It will also be seen that the effective area of the throat 111 is reduced as the throat portion moves further leftwardly with respect to the diverging conical wall portion itl? on the spike. The function of this will appear hereafter.

It may be commented that preferably the meeting wall portions are made smooth except for the spike point 66 and the leftmost edge of the diffuser element 98 which constitutes the receiving element for the stream and for the shock wave produced in it.

Operation As will be understood, as an example but not a limitation, the present jet pump or injector can usefully be connected into a boiler system, in which case the driving fluid can be water vapor and the driven iluid can be water. Water can enter the pump through the inlet 16 and can be ,conducted to the boiler by a pipe connected to the outlet 48. Saturated water is connected to the inlet of the nozzle 12.

The nozzle 12 has three stages. The driving fluid vapor enters the upstream end of the nozzle at subsonic speed, and is increased in velocity to sonic speed at the throat. Since at and above sonic speed, a diverging stream accelerates and drops in pressure, the nozzle passage diverges downstream from the throat, attaining supersonic velocities at the nozzle outlet where it meets the driven fluid. The mass flow rate of the drive fluid is xed by the crosssectional area of the throat of the nozzle. 1t is known what pressure drop must be available in order to attain sonic velocity at the nozzle throat for various drive fluids.

The steam or drive duid jet emitting from the nozzle 12 meets and accelerates the liquid phase coming in through the liquid inlet 16. The liquid is entrained into the mixing duct 2@ into which it is drawn in an annulus around the outside of the nozzle 12. The two fluids mix together in the mixing duct Z0, the velocity of the drive fluid being reduced while that of the mixture is increased. In this manner some of the thermal energy of the drive iluid is converted to mechanical energy, and, through momentum transfer, this energy is caused to accelerate the heavier body of the liquid phase. By the time the mass reaches the outlet end of the mixer tube, it is travelling at a more or less uniform subsonic velocity.

The mixing process occurs in a short section of duct which is so contrived that momentum diffusion proceeds at a faster rate than does thermal diffusion. By this means a majority of the momentum transfer has taken place by the time the mixture of the drive fluid and suction liquid leaves the mixing tube 19, whereas only a fraction, such as one-half, of the drive fluid vapor has condensed by the time the stream leaves the downstream end of the mixing tube. The pressure in the free space 36 usually is atmospheric. The length of the mixing tube is designed so that the Mach number of the mixture does not too closely approach unity at the tube outlet. The mean Mach number across the outlet may be about .8 or .9, thus restraining development of supersonic speeds at points across the outlet.

The operation of this pump is based upon the sonic characteristics of a vapor liquid mixture, typified in FIGURE 2 for steam. As the quality decreases from 1.00 to zero, the sonic speed of the liquid-vapor mixture changes from about 1300 feet per second down to about 70 feet per second at a quality of about 10r3. It then again increases rather rapidly to about 5,600 feet per second at 0.0 quality.

By charting the conditions previously specied, on F IGURE 2, it can be seen that the velocity of the mixture may be brought to the 20G-300 feet per second value aforesaid primarily by momentum transfer, and in any case with the thermal transfer so controlled that the quality of the mixture at this velocity is above that at which is velocity is supersonic. Therefore the conditions in the mixing tube can be kept subsonic, thereby avoiding complications that would result from the development of supersonic velocities therein. However, the momentum transfer desirably should be completed, and the iinal mixture velocity attained, at least approximately by the time the mixture reaches the downstream end of the tube Zd.

The combined fluids mass at the outlet of the tube Ztl, having reached a velocity such as 20G-300 feet per second, and are moving at a velocity that is subsonic so long as its quadty is kept relatively high, but which velocity is above the minimum possible sonic velocity of about 70 f.p.s. shown in FIGURE Z, attainable upon further reduction in quality. The mixture streams across the free space 3o, without substantial change of velocity or pressure. But in the free space, the continuing condensation of the drive fluid causes decline in quality of the mixture. This reduction of quality in the mass is accomplished by a reduction of its sonic velocity. Hence the mixture stream, without necessarily changing its own velocity, as it moves out across the gap, crosses the sonic velocity line in FIGURE 2 and attains supersonic velocity, such as Mach 2 or Mach 3, without the free area 36.

Before complete condensation of the drive iiuid, but after the mixture has reached supersonic speed, the diffusion begins. The reasons for providing the free space or gap across which the stream flows while relatively unconiined are (l) the momentum transfer' process between the driving iluid and the driven fluid can only occur etticiently if sonic velocity is not attained in the mixing tube; otherwise adverse pressure effects appear which seriously deteriorate the performance of the pump. @ptimum performance can only be obtained from the pump, however, if the mixed stream is allowed to become supersonic. Thus, the mixing tube is terminated before sonic velocity is reached, and condensation is allowed to produce a supersonic stream velocity in a free space; and (2) certain adverse boundary layer associated pressure etects are also avoided by the device of mixing tube termination to a free space.

The spike 62 is important to establish a proper conical shock wave in the supersonic stream. it is desirable to have the system as near isentropic as possible. Since a shock always involves some entropy increase, and such increase varies with a higher power of shock strength, the present arrangement uses the spike to reduce the magnitude of the initial shock, and causes,l instead of a single shock of higher magnitude, a series of shocks of smaller magnitude. The initial shock is developed by the spike tip 66, and the rest of the shock or compression process develops from redections from the walls and bends in the walls. The present system, therefore, while recognizing shocks as inevitable in the supersonic how, nevertheless regulates them to obtain the most favorable shock pattern.

Since at supersonic speeds pressure increases with decrease in cross-section of a duct, the diffuser conduit is made converging to its throat, and the pressure at the throat 54 of the diffuser becomes much higher than is attainable with a conventional subsonic speed injector.

The high pressure, high velocity stream developed as aforesaid, after passing the throat 54, becomes subsonic in velocity and follows characteristic laws of increased essere@ 'i7 pressure and decreased velocity as it emits through the diverging section 55.

ln the preferred form of diffuser arrangement illustrated especially in FIGURES 4 6, there is an automatically adjustable throat area, provided because of starting problems that exist in this type of system. For most operating conditions it is necessary, or at least desirable, that the diffuser throat area be larger for starting the pump than for optimum steady running conditions.

Similarly to the shock-caused starting problems in a supersonic wind tunnel, this jet pump requires a larger diffuser area at the start because of the shocks introduced in the deceleration of the supersonic fluid. Because of the two-phase character of the flow and the entrainment of a suction liquid, a larger diffuser throat than optimum is also required for suction-to-drive-fluid flow-rate ratios that are either less than or greater than optimum. For ratios that are less than optimum, insufficient drive vapor is condensed; and the volumetric flow-rate is too high to be swallowed. For ratios that are too high, the mixed fluid has a combination of high mass-flow rate and low velocity that again requires a larger diffuser area. Thus, because of both the supersonic and the two-phase natures of the flow, a variable diffuser throat area is required to achieve easy start as well as optimum, steady running conditions after the start is effected.

The throat area at the start in FIGURE 4 is at a maximum because the throat lll of the diffuser element 93 is disposed adjacent the relatively small neck portion 106 of the spike. This condition exists at the start because the discharge pressure is relatively low. Consideration of the opposing areas of the slidable diffuser element 98 subjected to the relatively high pressures upstream of the throat lll and the relatively low discharge pressures downstream of that throat will show that the springs 163 can maintain the diffuser element 9S in this positon at the start wherein there is maximum throat area. However, as the discharge pressure builds up by the increasing development of running conditions, such pressure acts on the downstream surfaces of the diffuser element 93 and moves it in an upstream direction. lts position is determined by the ratio of the discharge to incoming pressure. Such upstream movement of the element 92 introduces the throat lll over the conical portion 167 of the spike and causes the effective throat area to be reduced accordingly. When the running conditions are attained, the throat area will have its optimum size.

The diffuser element may be so designed that under normal conditions the optimum position is full to the left (i.e., upstream) or it may be designed to maintain its own optimum conditions by having the optimum position at some point between the two limits of travel. In the latter case, the diffuser element position would be determined by the pressure forces acting on the opposite facing surfaces.

Of course, it will be evident that the throat area can be adjusted for experimental purposes by adjusting the spike alone without the necessity of providing for the slidable diffuser element 98. Also other means may be provided for adjusting the throat area, either automatic or manual.

The mass flow rate ratio of driven fluid to drive fluid should be reasonably precisely controlled, for obvious reasons. This can be done by regulating the driven liquid flow rate. The drive fluid flow rate is controlled by the throat cross-sectional area of the drive fluid nozzle. A coarse adjustment is provided by the design of the mixing tube and the driven liquid entrance annulus around the nozzle 12. A fine control can be obtained by regulating the volume of liquid, as by a valve in the entrance 16. Too little suction fluid will not condense the drive vapor. Too high a liquid flow rate causes deterioration in the discharge pressure obtainable.

It is desirable to obtain condensation of all of the drive fluid before a significant part of the pressure recovery process. rThis avoids expending mechanical energy in recondensing the drive fluid, which energy is converted to thermal energy and hence is lost to creating discharge pressure.

On startup the flow may be somewhat rough so that the diffuser does not swallow all of it. In fact there is a good real of steam and water thrown around. It is necessary to provide a means of exhausting a large volume of this to the atmosphere until the proper flow can be established. It does not take long for the proper flow to be established, but if the excess fluid is not removed, it will prevent establishment of this flow. For this startup condition the shell 35 is moved all the' Way to the right, exposing a large air gap at the left hand end. The right hand flange 22 of the mixer 21 is smaller than the inside diameter of the shell 35. There are also three extra holes besides those drilled to take three spacer rods 33. All of these are for the purpose of allowing the excess fluid in the free space on startup to get out to the atmosphere. Other standard venting systems, such as ducting to atmosphere containing a check valve,could be used.

lt is possible to use the equipment illustrated for different values and fluids. This may require adjustment of drive fluid nozzle, and the use of different spacers to alter the gap across the free space 36. Also the spike can be adjusted to locate the apex of the shock wave cone appropriately with respect to the entrance of the diffuser.

The space 35 around the free jet is kept clear of extraneous gases, being filled only with the vapor of the drive fluid. As this vapor condenses, if the temperature of the Walls of the shell 35 is less than the liquefaction temperature of the vapor at the pressure therein, the condensate is withdrawn from the space and can be recirculated with the suction liquid. If the walls are at a high enough temperature to keep the fluid in vapor form, the vapor is sucked out of the space 36 as its vapor pressure tends to rise above the static pressure of the free jet.

It is considered that the usual region of operation of the pump is with a drive fluid having a quality between .2O and .0, the last point being that of saturated liquid. For drive fluid pressures of between 150 and 250 p.s.i.a., discharge pressures above 300 p.s.i'.a. can be expected. However, having a higher discharge pressure than the drive fluid pressure is not essential to the operation of the pump except where the pumpis used in a recirculating system. Most applications for the pump do involve recirculating systems, however; and they require that the discharge pressure of the pump be as far above the drive fluid pressure as there is pressure drop in the recirculating elements of the system.

The drawings given are considered to be diagrammatical, it being well known that sharp edges in the flow passages are undesirable, that the slope and proportions of the internal fluid passages will vary with the fluids used and the operating conditions, and that a more sophisticated heat transfer control is desirable.

It is of the essence of the present pump that it operate at supersonic velocities and that the shock waves be used as a means of increasing the pressure prior to the conventional subsonic diffusing operation.

Various changes and modifications may be made Within the process of this invention as will be readily apparent to those skilled in the art. Such changes and modifications are within the scope and teaching of this invention as defined by the claims appended hereto.

What is claimed is:

1. An injector pump comprising: a mixing tube hav` ing an inlet and an outlet end; means to introduce into the inlet end of the mixing tube a low speed driven liquid; means to introduce into the mixing tube a high speed driving fluid capable of becoming condensed by the driven liquid, the high velocity of the driving fluid impinging upon the driven liquid to cause the fluids to mix, move toward the outlet end, and emit therefrom with a velocity yabove theminimum sonic velocity of mixtures of the two, `but with the condensation of the driving fluid incomplete `so that the quality of the mixture is above that quality at which such velocity is supersonic, a supersonic diffuser having its entrance spaced from the outlet or" the mixing tube but positioned to receive the stream therefrom, means to maintain the integrity of the duid mixture in the spacebetween the mixer and the diffuser against influx of deleterious foreign uids, the space between the mixer and the diffuser being suiiicient to enable condensation of the driving fluid to continue far enough to render the stream velocity supersonic in the free space, the diffuser having its cross section gradually decreasing downstream from the entrance to a throat, the same being shaped to conduct the stream and to confine shock waves therein, whereby to raise the pressures therein.

2. The pump of claim l wherein the means to maintain integrity of the fluid in the free space between the mixing tube and the diffuser comprises an enclosure about said space.

3. The pump of claim l wherein the diffuser includes a tubular element to receive the stream and a central spike to cause the shock waves to be conical, and of relatively low magnitude, said spike, considered in a direction from upstream to downstream, being generally of diverging then converging shape, with the converging portion occurring where the stream is still supersonic.

4. The pump of claim l wherein the diffuser comprises a tubular element converging downstream to a throat, whereby the pressure may be increased in the liquid of the stream as the stream is increasingly reduced in diameter at supersonic speeds, until the Velocity at the throat is subsonic,

5. The pump of claim d wherein there is a diverging discharge passage downstream of the throat to reduce velocity and increase pressure in the stream.

The pump of claim l. with means to adjust the space between the mixing tube and diffuser to set the proper travel of the stream to attain the optimum quality for optimum pressure recovery from the supersonic stream.

7. The pump of ciairn 3 with means to adjust the position of the spike axially of the pump.

3. The pump of claim wherein the diffuser includes a casing and a diffuser element therein, the element providing a converging passageway tapering downstream to a throat, and means to adjust the size of the throat to be relatively larger at the start of operation and relatively smaller during ruiming conditions.

S. The pump of claim 3 wherein the diffuser also includes a spike element within the converging passageway and substantially coaxial therewith, the spike element having converging walls adjacent the throat of the diffuser element, and means for producing relative axial movement between the spike element and the diffuser element to alter the effective area of the throat.

itl. The pump of claim 9 wherein one of the two elements is axially movable with respect to the other, with resilient means normally urging it in a direction to provide the maximum size of the throat area, and with pressure-receiving walls subjected to discharge pressure and oppositely subjected to pressure upstream of the throat whereby it can be moved against the resilient means as discharge pressure increases, so that when discharge pressure is relatively low the throat area is relatively large, but as discharge pressure increases, the throat area is reduced.

il. A process of attaining high pressure in a liquid, comprising impinging upon the liquid a high velocity stream of a vapor condensible in the liquid, confining the mixture in said stream and increasing the velocity of the liquid by the vapor stream, until the velocity of the mixture is below the minimum sonic velocity of mixtures of the liquid and vapor of various qualities, causing the mixture to attain such velocity in the stream prior to condensation of all of the vapor and at a quality such that its velocity is subsonic, continuing the condensation as the stream moves and reducing the quality thereof so that the stream velocity becomes supersonic, and then diffusing the stream at supersonic velocity by gradually restricting its cross section and raising the pressure therein by pressure waves, and causing the final stage of vapor condensation to occur in the diffusion process, with essentially all of the vapor being condensed by the time the stream reaches a predetermined minimum cross section.

i2. A process of attaining high pressures in a liquid, comprising producing a mixed stream of a liquid and a vapor condensible or absorbable by the liquid, having a velocity above minimum sonic velocity for mixtures of the liquid and vapor or" various qualities, and of a quality outside the range or qualities at which such velocity is supersonic, thereafter causing condensation ot the vapor to occur to change the quality until it becomes within the range of supersonic velocities and the velocity of the mixture is supersonic, and diffusing the stream while it is at supersonic velocity to increase its pressure.

i3. The process of claim i2 wherein the stream becomes supersonic while it is relatively unconlined, and then is caused to impinge upon a spike s-o as to make conical shock waves, and wherein the shock waves are swallowed and reflected while being held to relatively low magnitude during the diffusion of the mass to subsonic velocities.

i4. The process of claim 12 wherein the stream is diffused by being restricted in cross section until it attains a predetermined minimum section, and wherein the velocity at such minimum section is subsonic, and thereafter enlarging the section of the stream while confining it at subsonic velocities.

i5. ln a pump of the kind described: a high velocity fluid nozzle and a low velocity liquid inlet; a tubular mixer having an entrance adjacent the nozzle to receive the high velocity fluid, the mixer having a space communicating with the liquid inlet whereby liquid may enter the mixer and the high velocity fluid may drive the liquid through the mixer, producing a liquid-fluid mixture flowing from the mixer at high velocity; a supersonic diffuser device spaced from the outlet end of the mixer to receive a stream emitted therefrom, comprising a tubular diffuser element and a spike element therein, the diffuser element and spike element being shaped to provide a gradually reducing cross section to a throat of minimum cross section; an enclosure surrounding the space between the mixture and the diffuser device; the diffuser element and spike element being relatively movable to alter the cross section of the throat; a housing downstream of the diffuser device and into which the diffuser element discharges, one of said diffuser and spike elements being movable relatively to the housing, as well as to the other such element, and having a pressure-surface exposed to the pressure in the housing, and means acting yieldably to urge the said movable element oppositely to its movement Iin response to the pressure in the housing; whereby decrease in pressure in the housing causes the element to move in a direction to increase the throat size.

i5. A process of producing predetermined outlet pressures in a liquid, including the steps of: directing a condensible drive fiuid at high velocity into the driven liquid, and confining the mixture to produce a flowing stream of the mixture; causing the drive iluid to accelerate the driven liquid yby momentum diffusion in the confined stream; causing the drive fluid to condense in the driven liquid as they tiow in the stream; completing the momentum diffusion prior to completion of the condensation of the drive fluid, and producing a stream velocity upon completion of the momentum diffusion that is subsonic for the quality of the mixture at that point, but which is supersonic at lower quality; thereafter completing the condensation in the stream and lowering its quality without substantial change in velocity and thereby causing the attained velocity to become supersonic; then diffusing zeef/ea l i. the supersonic stream by coniining it and'reducing its cross section, and thereby raising its pressure to the predetermined value.

17. In the process of claim 16, the step of freeing the stream from its connement prior to its attaining supersonic velocity so that the thermal energy exchange between the drive fluid and the driven liquid can be completed without substantial change in volume.

1S. The process of claim 15, wherein the diffusing step includes directing the supersonic stream against a point so as to produce a conical pressure wave in the stream, swallowing the stream and continuously decreasing its cross section to a predetermined minimum section, and producing reflected waves in the stream as it decreases in section.

i9. The process of claim 16, wherein the diffusing step includes reducing the cross section of the stream until it becomes subsonic in velocity; and wherein it thereafter is further reduced in velocity and increased in pressure.

Ztl. The process of claim 16, wherein the drive iiuid is directed against the driven fluid at supersonic velocity, and the momentum diiusion reduces the velocity to subsonic value.

21. The process of claim 20, wherein the drive tluid is initially restricted until it attains supersonic velocity, thereafter is enlarged in cross section to increase its velocity and to be directed against the driven liquid as aforesaid.

22. in a process of obtaining a pressure increase in a two phase Huid mixture comprising a liquid and a condensible vapor; the steps of: causing the mixture to flow in a stream at a velocity that is subsonic for its quality but which velocity is supersonic for lower quality mixtures; causing condensation of the vapor to occur in the stream, and reducing the quality so that the velocity becomes supersonic as a result of the quality change; diffusing the supersonic stream, gradually reducing its cross section, and increasing its pressure while its quality is further decreased and its velocity becomes subsonic. 23. In a proc/ess for producing a supersonic stream from a iiuent material, the steps of: directing a high- 5 velocity condensible vaponphase uid against a louvelocity liquid; transferring energy from the highfv'elocity u-id to the liquid by causing momentum transfer and by causing condensation of the high-velocity fluid, while confining the mixture; substantially completing the momentum transfer prior to completion of the condensation; releasing thc stream from the coniinement at a velocity that is subsonic for the quality of the mixture at t'ne point of release, and prior to completion of the condensation; and then continuing the condensation as tne stream iiows, and reducing the quality until the velocity of the stream becomes supersonic by virtue of they reduction in the Mach I curve for the two-phase material being used.

References Cited by the Examiner OTHER REFERENCES neass: Practice and Theory of the Injector, 1894, pages 107-8 (lohn Wiley and Sons, New York).

Baumeister: Marks Mechanical Engineers Handbook, 1958, pages 11-97, sixth edition (McGraw dill Co., New York).

LAURENCE V. EFNER, Primary Examiner.

IOSEPH H. BRANSON, JR., RGBERT M. WALKER Examiners. 

1. AN INJECTOR PUMP COMPRISING: A MIXING TUBE HAVING AN INLET AND AN OUTLET END; MEANS TO INTRODUCE INTO THE INLET END OF THE MIXING TUBE A LOW SPEED DRIVEN LIQUID; MEANS TO INTRODUCE INTO THE MIXING TUBE A HIGH SPEED DRIVING FLUID CAPABLE OF BECOMING CONDENSED BY THE DRIVEN LIQUID, THE HIGH VELOCITY OF THE DRIVING FLUID IMPINGING UPON THE DRIVEN LIQUID TO CAUSE THE FLUIDS TO MIX, MOVE TOWARD THE OUTLET END, AND EMIT THEREFROM WITH A VELOCITY ABOVE THE MINIMUM SONIC VELOCITY OF MIXTURES OF THE TWO BUT WITH THE CONDENSATION OF THE DRIVING FLUID INCOMPLETE SO THAT THE QUALITY OF THE MIXTURE IS ABOVE THAT QUALITY AT WHICH SUCH VELOCITY IS SUPERSONIC, A SUPERSONIC DIFFUSER HAVING ITS ENTRANCE SPACED FROM THE OUTLET OF THE MIXING TUBE BUT POSITIONED TO RECEIVE THE STREAM THEREFROM, MEANS TO MAINTAIN THE INTEGRITY OF THE FLUID MIXTURE IN THE SPACE BETWEEN THE MIXER AND THE DIFFUSER AGAINST INFLUX OF DELETERIOUS FOREIGN FLUIDS, THE SPACE BETWEEN THE MIXER AND THE DIFFUSER BEING SUFFICIENT TO ENABLE CONDENSATION OF THE DRIVING FLUID TO CONTAINUE FAR ENOUGH TO RENDER THE STREAM VELOCITY SUPERSONIC IN THE FREE SPACE, THE DIFFUSER HAVING ITS CROSS SECTION GRADUALLY DECREASING DOWNSTREAM FROM THE ENTRANCE TO A THROAT, THE SAME BEING SHAPED TO CONDUCT THE STREAM AND TO CONFINE SHOCK WAVES THEREIN, WHEREBY TO RAISE THE PRESSURES THEREIN. 